I just saw this bug, https://bugzilla.novell.com/show_bug.cgi?id=459792,
that reports a problem in OpenSUSE with Grub being unable to boot with
XFS when someone upgraded from OpenSuSE11.0 to OpenSuSE11.1.
Grub is unable to start if /boot is on xfs partition.
Found after updating from 11.0 to 11.1.
Response from Novell:
------- Comment #1 From Jiri Srain (jsrain(at)novell(dot)com) 2008-12-18 04:24:39 MST
We agreed with product management that /boot on XFS will not be a supported
bootloader scenario. See relevant thread on factory to see explanations;
successful booting from XFS is just a pure luck.
Perhaps if Grub can't support XFS, the default bootloader should
be upgraded to 'lilo' -- as it still seems to be maintained and still
supports high performance file systems like XFS.